Penetration into a patient's pleura or lung parenchyma often results in air leaking into the pleural cavity, referred to as “pneumothorax”. In addition to chest injury, disruption of the sealed pleural and thoracic space may also result from thoracic surgery. Increased intrapleural pressure from air leakage can cause a lung to collapse. Accordingly, a chest tube is often inserted in the pleural cavity to drain fluid and restore negative pressure in the intrapleural space of patients that have undergone lung surgery, surgery of adjacent organs, or suffered injury to lung tissue as a result of any type of chest trauma.
One method of chest drainage involves a chest tube fluidically coupled to a drainage canister. In some embodiments, the drainage canister includes a “3-bottle set-up”, such as the PLEUR-EVAC system produced by TELEFLEX INCORPORATED or the OCEAN WET SUCTION WATER SEAL DRAIN produced by ATRIUM MAQUET GETINGE GROUP. The three bottles may include a collection bottle, a water-seal bottle, and a suction-control bottle. Suction is applied to the pleural cavity to withdraw fluid, including air “Pneumothorax” from an air leak and liquid “Hemothorax”. Any gas withdrawn from the pleural cavity enters the collection bottle and passes into the water-seal bottle where it bubbles through water. The water in the water-seal bottle acts as a one-way valve preventing back flow of gas into the chest cavity. Clinicians typically detect air leaks by visually observing bubbles within the water-seal bottle. However, any detection, measurement, or grading of an air leak is prone to inconsistency caused by observer subjectivity and human error. The anatomy and physiology of the pleural space and the chest wall can lead to false positive detection of air leaks with current clinical methods (e.g. visual observation of bubbles and chest x-rays). Retained air within the pleural space may change position because of pleural space tissue movements, even when the bronchial and parenchymal leak site has been healed. Movement of retained air results in a delay in the removal of the chest tube and a subsequent increase in the morbidity rate, possible complications, patient discomfort, and unnecessary extension of hospital stay. Additionally, false negative detection of an air leak may occur when small leaks are concealed by collapsing tissues.
Air leaks are one of the most common complications after trauma in the thoracic space, as well as an expected medical problem after thoracic surgery. Air leaks are a common cause of prolonged hospitalization, adding significantly to the cost of medical care. See Cerfolio R J, Bass C S, Pask A H and Katholi C R. Predictors and treatment of persistent air leaks. Ann Thorac Surg 2002; 73: 1727-1730. Furthermore, patient recovery is difficult to assess with the currently employed detection and monitoring techniques (e.g. visual observation of bubbles and chest x-rays). Currently, it is customary to establish negative pressure suction for a specified time following a following a traumatic chest injury and/or thoracic surgery. This decision is done empirically and results in the inability to objectively monitor and customize treatment according to the healing/sealing process of the bronchial tree and lung parenchyma.